1. Field of the Invention
The present invention relates to a laser distance-measuring device, more particularly, to a laser distance-measuring device capable of easily measuring a horizontal distance.
2. Description of the Related Arts
Laser distance-measuring devices have been widely used in a variety of applications, such as power engineering, hydraulic engineering, architecture, geographic investigation, and athletic ranging, for measuring distance between two stationary objects.
U.S. Pat. No. 6,624,881 describes a conventional laser distance-measuring device. The device comprises a microcontroller, a non-erasable memory, a mass memory, a keypad, a display, a radiation source, and a radiation receiver. The microcontroller controls the radiation source to emit a modulated laser beam. The laser beam is received by the radiation receiver after being reflected by a target object, and is modulated by the microcontroller. The time that the laser beam takes during the journey is recorded, and is multiplied by a propagation velocity of the laser beam to determine the distance that the device is distant from the target object. Data of measurement are stored in the mass memory, and the result is shown on the display. In addition, operation modes and correction algorithms, which are stored in the non-erasable memory, can be selected through the keypad for desired result of measurement.
Although the conventional laser distance-measuring device can measure a straight distance of an object from the device, it has difficulty to measure a distance between two spaced points, which often happens in the fields of architecture and construction. For example, workers usually need to measure the height of a wall, a tree, or a building.
Referring to FIG. 4 of the attached drawings, to measure the height C of for example a building, the conventional laser distance-measuring device detects distances A and B first, and height C is then figured out by Pythagorean theorem. Distance A represents a horizontal distance that is perpendicular to C, and distance B represents a hypotenuse in the right triangle. However, when an obstacle, which blocks the laser beam, is present in the trace of A, it is not possible to measure the distance A and thus it cannot calculate the height C. This happens very often in practical applications, and makes the measurement of height C difficult.
On the other hand, U.S. patent application Ser. No. 10/813,065, filed by the Applicant on Mar. 31, 2004, discloses an inclinometer, which comprises a signal sampling circuit that can be employed in a laser-leveling device. The inclinometer has an output pin, on opposite sides of which a pair of first input pins and a pair of second input pins are symmetrically arranged, and an electrolyte conducting between the first input pins and the output pin, and between the second input pins and the output pin. The signal sampling circuit includes a signal-generating module, a sample-and-hold module, and a difference module. The signal-generating module generates a plurality of level-measuring signals at fixed intervals. The level-measuring signals are applied to the first input pins and the second input pins alternately, thereby outputting a plurality of corresponding first output signals and second output signals in the output pin. The first output signals and the second output signals are sampled and held by the sample-and-hold module, and first sampling signals and the second sampling signals are output. The difference module receives the first sampling signals and the second sampling signals, and determines the difference between the first and second sampling signals. The difference is converted into a level-measuring signal, which is applied to a microcontroller. The microcontroller then works out the current inclination.
Thus, the present invention is aimed to provide a laser distance-measuring device in combination with an inclinometer to enhance the operability and precision of measurement thereof.